1. Field of the Invention
This invention relates to a gimbal which can move on all three axes, particularly a gimbal having a support surface for an article which can move same into a desired position and accurately sustain said position.
1. The Prior Art
In the production of components, e.g., electrical components, there is often a requirement for locating microscopic defects therein so as to reject or repair such components and improve the quality of the product. For example, it is necessary to inspect electrical substrates, e.g., a printed wiring assembly (PWA) using small components. In the prior art, such substrate is held by hand under a microscope and is turned at various angles that the viewer may see defects, e.g., at the soldered joints thereof. The viewer attempts to memorize the coordinates of the defect, puts the substrate down, e.g., on a work surface and enters the coordinates into a mapping system or attempts to hold the substrate in place under the microscope with one hand, while operating, e.g., an inspection digitizing system (IDS). Of course, under a microscope a slight tremor of the hand can move the substrate and located defect out of focus and/or out of position, causing the recording of erroneous data and inaccurate mapping of such defects. Even if the substrate be held accurately under the microscope, the arm soon tires and becomes less steady. Meanwhile the viewer has but one other arm to operate the above IDS or other equipment or to make notes and, of course, cannot move about without removing the substrate from the viewing field.
What is needed is an apparatus which can position a substrate in the above viewing field with sustained accuracy, so as to free the viewer's hands to perform other tasks, operate other equipment, to make notes thereof and the like.
Looking at the prior art, one sees a clamping means with a ball and socket base for holding a loudspeaker, U.S. Pat. No. 4,765,580 (1988) and a leveling stage of limited movement relative to a reference plane, U.S. Pat. No. 4,226,569 (1980).
Thus, both the above clamping means and leveling stage are able to tilt but otherwise display confined movement near their respective support surfaces.
On the other hand, U.S. Pat. No. 4,577,819 (1986) discloses a boom apparatus which has considerably greater range of movement of boom pivoting around a support post in the vertical plane as well as in the horizontal plane. However, here the boom cannot accurately sustain its position in the vertical plane and must be locked at three points thereon by spring-loaded plunger 88 (FIG. 4) and thus displays limited or 3 point stability in such plane, which while fine for the intended purpose of mobility of a welding apparatus at the distal end of such boom, would not be satisfactory for freely positioning an article in a microscopic field with sustained accuracy.
Thus the prior art does not suggest an accurate positioning mechanism, e.g., in a microscopic field, and there is a need and market for an accurate inspection apparatus that overcomes the above prior art shortcomings and frees the hands of the viewer for complementary or other tasks.
There has now been discovered an inspection apparatus which has the flexibility and range of movement associated with hands-on feeling of inspection, which provides the necessary positional accuracy for mapping of small components and which frees the hands for other duties.